Candida is a genus of yeasts. Many species of this genus are endosymbionts of animal hosts including humans. While usually living as commensals, some Candida species have the potential to cause disease. Clinically, the most significant member of the genus is Candida albicans, which can cause infections (called candidiasis or thrush) in humans and other animals, especially in immunocompromised patients. Many Candida species are members of gut flora in animals, including C. albicans in mammalian hosts, whereas others live as endosymbionts in insect hosts.
Among the other important members of this genus Candida dubliniensis is a significant pathogenic fungi. Candida dubliniensis is an organism often associated with AIDS patients but can be associated with immunocompetent patients as well. It is a germ cell-positive yeast of the genus Candida, similar to Candida albicans but it forms a different cluster upon DNA fingerprinting. It appears to be particularly adapted for the mouth but can be found at very low rates in other anatomical sites. Candida dubliniensis is found all around the world. The species was only described in 1995. It is thought to have been previously identified as Candida albicans. Retrospective studies support this, and have given an indication of the prevalence of C. dubliniensis as a pathogen.
This isolate is germ tube positive which accounts for its historic miss-identification as C. albicans. The most useful test for distinguishing C. dubliniensis from C. albicans is to culture at 42° C. Most C. albicans grows well at this temperature, but most C. dubliniensis do not. There are also significant differences in the chlamydiospores between C. albicans and C. dubliniensis although they are otherwise phenotypically very similar.
A study done in Europe of 2,589 isolates that were originally reported as C. albicans revealed that 52 of them (2.0%) were actually C. dubliniensis. Most of these isolates were from oral or faecal specimens from HIV positive patients, though one vaginal and two oral isolates were from healthy volunteers. Another study done in the United States, used 1,251 yeasts previously identified as C. albicans, it found 15 (1.2%) were really C. dubliniensis. Most of these samples were from immunocompromised individuals: AIDS, chemotherapy, or organ transplant patients. The yeast was most often recovered from respiratory, urine and stool specimens. The Memorial Sloan-Kettering Cancer Center also did several studies, both retrospective, and current. In all 974 germ-tube positive yeasts, 22 isolates (2.3%) from 16 patients were C. dubliniensis. 
Molecular analysis show that C. dubliniensis is distinct from C. albicans by 13-15 nucleotides in the ribosomal RNA gene sequences. Early reports purported that C. dubliniensis was responsible for fluconazole-resistant thrush but susceptibility studies reveal that its categorical distribution is similar to C. albicans with isolates ranging from susceptible to resistant.
Previous literature describes that Centromeric DNA sequences in the pathogenic yeast Candida albicans are all different and unique (Sanyal et al, 2004). The Cse4p-containing centromere regions of Candida albicans have unique and different DNA sequences on each of the eight chromosomes. However similar studies have not been carried out in C. dubliniensis. 
Amongst the most prevalent methods of distinguishing C. dubliniensis from C. albicans are the compositions and methods for the detection and identification of species of Candida, in particular, to nucleic acid probes that specifically hybridize to the internal transcribed spacer 2 (ITS2) of the ribosomal DNA (rDNA) repeat region of Candida species (such as C. albicans and C. dubliniensis).
Another method of identification includes use of multiplex PCR which uses essentially three factors: (i) the elevated number of copies from the rRNA genes (about 100 copies per genome), (ii) the differences regarding the sizes of the ITS regions and (iii) the elevated variability of these region sequences among the different species of Candida. Thus, this technique is based on the amplification of DNA fragments specific of the internal transcribed spacer regions 1 (ITS-I) and 2 (ITS-2) by multiplex PCR. The methodology uses the combination of two universal primers and seven specific primers for each one of the Candida species studied, in a single PCR reaction, originating two fragments of different sizes for each species (European publication no: EP1888745).
Most techniques used so far distinguish C. dubliniensis from other species by identification of rDNA or RNA sequences of the genome.
The genome of C. dubliniensis has not been sequenced completely and the work to find out more information about its genome is in progress.
However the present invention has been able to assign centromeric functions to the sequence identified and these centromeric sequences are further used to distinguish Candida dubliniensis from other members of the genus based on the localization of histone proteins CdCse4p.
Faithful chromosome segregation during mitosis and meiosis in eukaryotes is performed by a dynamic interaction between spindle microtubules and kinetochores. The kinetochore is a proteinaceous structure that forms on a specific DNA locus on each chromosome, termed as the centromere (CEN). Centromeres have been cloned and characterized in several organisms from yeasts to humans. Interestingly, there is no centromere-specific cis-acting DNA sequence that is conserved across species (1). However, centromeres in all eukaryotes studied to date assemble into specialized chromatin containing a histone H3 variant protein in the CENP-A/Cse4p family. Members of this family are called centromeric histones (CenH3s) and are regarded as possible epigenetic markers of CEN identity (1, 2). The Saccharomyces cerevisiae centromere, the most intensively studied budding yeast centromere, is a well defined, short 125 bp) region (hence called a “point” centromere), and consists of two conserved consensus sequences (Centromere DNA Elements; CDEs), CDEI (8 bp) and CDEIII (25 bp) separated by CDEII, a 78-86 bp non-conserved AT-rich (>90%) “spacer”-sequence (3). CDEI is not absolutely necessary for mitotic centromere function (4). Retention of a portion of CDEII is essential for CEN activity, but changes in length or base composition of CDEII cause only partial inactivation (4, 5). The S. cerevisiae CenH3, ScCse4p, has been shown to bind to a single nucleosome containing the non-conserved CDEII and to flanking CDEI and CDEIII regions (6). CDEIII is absolutely essential: centromere function is completely inactivated by deletion of CDEIII, or even by single base substitutions in the central CCG sequence. Centromeres of most other eukaryotes, including the fission yeast Schizosaccharomyces pombe, are much longer and more complex than those of S. cerevisiae and are called “regional” centromeres (3). The centromeres of S. pombe are 40-110 kb in length, and organized into distinct classes of repeats which are further arranged into a large inverted repeat. The non-repetitive central region, also known as the central core (cc), contains a 4-7 kb non-homologous region that is not conserved in all three chromosomes (3). The CenH3 homolog in S. pombe, Cnp1p, binds to the central core and the inner repeats (7). However, the central domain alone cannot assemble centromere chromatin de novo, but requires the cis-acting dg/K repeat present at the outer repeat array to promote de novo centromere assembly (8, 9). Several experiments suggest that unlike in S. cerevisiae, no unique conserved sequence within S. pombe centromeres is sufficient for establishment and maintenance of centromere function, although flanking repeats play a crucial role in establishing heterochromatin that is important for centromere activity (10). Studies in a pathogenic budding yeast, Candida albicans, containing regional centromeres suggest that each of its eight chromosomes contains a different, 3-5 kb, non-conserved DNA sequence that assembles into Cse4p-rich centromeric chromatin (11, 12). C. albicans centromeres partly resemble those of S. pombe but lack any pericentric repeat that is common to all of its eight centromeres (12). Therefore, the mechanisms by which CenH3s confer centromere identity, are deposited at the right location, and are epigenetically propagated for several generations in C. albicans without any centromere-specific DNA sequence remain largely unknown.